Well flow device



Allg- 9, 1949- I l.. HARTM-AN 2,478,483I

WELL FLOW DEVICE Lljndorz L. `Hor-hymn INVENTOR.

ATTORNEY.

Aug. 9, 1949. 1 HARTMAN WELL FLow DEVICE 2 sheets-sheet Filed May 17, 1946 lmf Psienied Aug. 9, '19,49

UNITED STATES PATENT OFFICE WELL ELow DEVICE Lyndon L. Hartman, Dallas, Tex. Application May 17, 1946, serial No. 670,502

Claims.

actuated by the pressure differential thereacross,l that is, one side of the valve is exposed to the lifting fluid and its opposite side is exposed to the pressure of the liquid within the tubing. Thus, when the well liquid pressure reaches a point sufficient to overcome the lifting fluid pressure holding the valve closed, said valve is opened to admit the lifting fluid to the tubing and raise the liquid. However, the single valve does not satisfactorily change the volume of lifting fluid after the liquid column is in motion and therefore, a smoothr lifting action is not obtained.. It is obvious that once the liquid column is in motion, less volume of lifting fluid is required to keep it moving upwardly than was needed to begin flow and in order to conserve the lifting uid, as well Aas to provide a smootherV action, it is desirable reduced.

that the volume of admitted 'lifting fluid be Another disadvantage of the singledifferenfially actuated valve is that so long as the lifting fluid pressure in the annular space outside the tubing remains substantially constant, the operation is satisfactory because then the pressure of the liquid must build up to substantially the same point each time to open the valve. However, in instanceswhere the annular space outside the 'tubing is in communication with sub-surface lforinationa pressure' from` such` formations is xaddedtbl theliftin'g -uid pressureto increase the same. When this occurs, theV pressure vdifferen- "tial" across the main valve necessary toopen said valve may remain the same but the pressures fon -opposite sides of said valve are changed. In

other words, assuming that al differential of pounds across said valve is required to open the f valve `and that the lifting fluid pressure is normally 300 pounds, then the Well'liquid pressure would have to reach350 pounds to open the valve.` If the lifting iuidipressure built up to 350 pounds due t the addition ofiformation pressure, the

increase in the lifting fluid pressure could build up to a point where the well liquid pressure could not overcome it and the valve would be rendered inoperative. For this reason, it is essential that the pressure of the lifting fluid in the annular space outside the tubing be controlled and maintained substantially constant.

It is one object of the present invention to provide an improved well flow device for controlling the admission of a-lifting fluid, such as gas or air into a liquid column within a well tubing or conductor and which has its' valve mechanism so constructed that the volume of lifting fluid is automatically varied during operation of the device and in accordance'with the changing conditions and requirements, whereby more eiilcient lifting of the well liquid is accomplished.

An important objectof the invention is to provide an improved Well flow device wherein a plurality of valve elements are mounted for individual actuation, with each element being operated under a predetermined pressure differential which operating differential is different from that of the others, whereby thevvalve elements close progressively or in succession at spaced intervals and in accordance with the changing differential produced by the flowing .well liquid column; the successive actuation of the valve elements effecting a change of volume of lifting fluid being admitted to the liquid column, whereby the required volume of lifting fluid is introduced into the liquid column throughout the entire cycle of operation of the device.

Still another object of the invention is to provide an improved well ow device, of the character described, wherein a plurality of valve elements are mounted for actuation by the differential in pressure of the lifting fluid and the pressure of the liquid column to be lifted; each valve `having associated therewith a resilient means,

such as a spring, which controls or sets the differential at which vsaid valve is to operate and the resilient means of each valve being different from the resilient means of the others so that the valves areA actuated by various predetermined pressure differentials, said valve elements being mounted to telescope one within the other whereby a simple ycompact device is had. 4

A further obj ect of the invention is to provide a valve device having valve elements each of which 'is arranged to operate upon a pressure differenwelly liquid. pressure would have to4 attain 400 pounds'.Y Itthusbecomes obvious that continued tial thereacross, Awith the differential actuating one valve element-being dissimilar from the differentials which operate the -other elements, whereby a change in volume of the fluid controlled by the device is affected as` the valve elements progressively operate; the device being particularly adapted for use as a well flow device for admitting lifting fluid intoa well liquid column but being so arranged that it may be employed for controlling the flow of any iiuid in other types of mechanisms.

An important object of the invention is to provide an improved well ow device which is so constructed that its valve elements may be rearranged in another position and in such event the device will operate to maintain the pressure vdifferential required to actuate the valve, substantially constant regardless of possible changing p. assure conditions which may occur on one side of the device and which would normally vary the differential necessary to operate said valve.

Another object of the invention is to provide an improved flow device, of the character described, wherein a main valve, which controls the admission of lifting fluid into the well liquid column, has one side exposed to the lifting iluid pressure and its opposite side exposed to the well liquid pressure whereby said valve is actuated by a predetermined differential between said pressures; the device also including means for main,-l -taining the lifting fluid pressure which acts on one side of the valve substantiallyl constant, whereby the pressure of vthe well liquid column will build up to substantially the same point within the well conductor before the valve is actuated to admit lifting fluid to said liquid column.

A particular object of the invention is to provide an improved well flow device having two valve elements which may be arranged to be actuated by a pressure differential thereacross, with the differential necessary to actuate one valve element being different from the differential required to actuate the second valve, whereby the device functions as a lifting fluid device which automatically varies the volume of admitted fluid during its operation; said valve elements being adapted to be rearrangedso that one functions as a differentially actuatedv valve for controlling the admission of the lifting uid while the other acts merely as a relief or stabilizing valve so as to prevent the pressure acting on one side of the first valve from exceeding a predetermined point, whereby eiilcient operation of said first valve is assured.

The construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specication and by reference to the accompanying drawing,

wherein an example of the invention is shown,

and wherein:

Figure 1 is a view, partly in section and partly in elevation of a well bore having a well tubing or conductor extending therethrough and having a well flow device, constructed in accordance with the invention, mounted in said tubing,

Figure 2 is an enlarged, transverse; sectional view of the ilow device. showing the valve elements functioning as a lifting fluid control device, with both valves in an open position,

Figure 3 is a similar view, with the outer valve closed and the inner valve open,

Figure li is a similar view with both valve elements closed,

Figure 5 is a horizontal, cross-sectional view, taken on the line 5 5 of Figure 3, and

Figure 6 is a view similar to Figure 2, and illustrating the valve elements rearranged, whereby Inl the drawings, the letter A designates a vwell bore having a well casing I0 therein.. A well tubing II extends downwardly through the casing I0 and has its upper end supported in the usual casing head I2 which is mounted on the upper end of said casing. The lower end of the well tubing has the conventional well screen, through which the well fluids are admitted into said tubing, attached thereto.

The improved well ilow device B is arranged to be connected in the'tubing or well conductor I I and is located at the desired. elevation or level in accordance with the particular well conditions. If desired, a plurality of the devices set to operate under different pressure conditions, as will be hereafter disclosed, may be disposed at various elevations inthe tubing. The valve device is arranged to control the admission of a lifting fluid such as gas or air into the well tubing or conductor II so that such iluid may' raise or lift the well liquids upwardly through said tubing to the surface. scribed as operating with an auxiliary lifting fluid, such as gas, but it is noted that the lifting fluid may be gas from a sub-surface formation which is conducted into the well casing. The

auxiliary lifting iiuid or gas is conducted to the annular space between the well casing I'll and the well tubing II through an inlet pipe I4. which is connected to the casing I2. With the arrangement illustrated, the lifting fluid is introduced into this annular space and fllls said space, with the pressure of the lifting fluid being maintained at a desired point. The presence of a lifting fluid under pressure within the annular space surrounding the well tubing causes the well liquids which flow from the formation to enter the lower end of the well tubing and rise upwardly to a normal standing level within said tubing. It will be noted that the lower portion of the annular space is not packed ofi' from the formation with the result that any gas within said formation may enter said annular space. The entrance of this gas may act to increase the pressure within the annular space and the. flow device B, as will be explained, not'only controls the admission of the lifting uid into the well tubing but may bel slightly ymodified to function to maintain the'v pressure of the lifting fluid Within the annular space substantially constant, regardless of the volume of gas or increased pressure which may result from entry of fluids from the formation into said annular space.

The construction of the valve device B is clearthis manner the housing is connected to and supported by said tubing. The bore 20 of the housing communicates with the interior of the well The invention will be herein de-v extends through the. boss l1 andpin I8. The

upper end of the housing is closed by a cap member or plug |5a which threads into said housing.

The lower end of the housing I5 has a closure 22 threaded thereon and as is clearly shown in Figure 2 said closure has inlet openings 23 there-- in. The coupling I 6 has an axial bore I6a extending entirely therethrough and it is apparent that a ow from exteriorly of the housing may occur through the inlet openings 22, bore I6a of the coupling, bore 20 of the housing and finally into the well tubing I l through the radial port 2|.

An annular valve seat 24 is formed on the lower end of the coupling I6 and surrounds the lower portion of the bore 16a thereof. A tubular valve element 25 is movable axially through the bore IEa of the coupling I6 and has its ends projecting beyond the upper and lower ends of said coupling. The lower end of said valve element has a valve head 26 integral therewith and this head includes a conical seating surface 21 which is adapted to engage a valve seat 24 of the coupling IE; when the valve element is in a seated position, flow through the bore Ila of the coupling is closed. The valve element 25 and head 26 are formed with an axial bore 28 extending entirely therethrough and the upper portion of the element is provided with radial stop lugs or projections 29 which prevent downward displacement of the element from the bore .16a of the coupling. If desired, a valve head (not shown) could be provided at the upper end of the element to prevent reverse flow through the bore I6a.

The valve element 25 is normally urged downwardly toward an open-ed or unseated position by a coil spring 30 which is located within the bore 20 of the housing l5 and which has its lower end engaging the upper end of the valve element. The upper end of the spring 30 is confined within an annular recess 3| which is formed in the underside of an adjusting bushing 32, the latter being threaded into the upper end of the hous-` ing below the cap or plug I5a. The'spring 30 is of the housing, whereby the valve is actuatedby the differential in such pressures. The pressure of the spring 30 is added to the well liquid pressure and is predetermined and thus it is obvious that the well liquid pressure must reach a predetermined point before the valve element will be moved downwardly to an unseated position against the pressure of the lifting fluid.

A second valve member 33 is slidable within the axialbore 28 of the valve element 25. The member 33 includes a central shank portion which is formed with longitudinal grooves or channels 34 and the lower end of the member has a valve head 35 threaded thereinto. When the member is in a raised position (Figure 4) the valve head engages a valve seat 36 formed in the lower end of the bore 28 of the outer valve element. When in such position flow through the bore 28 and through the grooves orchannels 34 is prevented.

The upper end of the valve member 33 is formed with stop lugs or projections 31 to prevent downward displacement of the member through 6 the bore 28 of the element 25. Ii' desired. this member may have a valve head at its upper end to prevent reverse ilow through the bore 28. The valve member 33 is urged downwardly toward an unseated position by a coil spring 38 which is disposed within the larger spring 30 and which has its lower end engaging the upper end of the member. The upper member of the spring 38 is disposed within an annular groove 39 provided in the lower surface of the adjusting bushing 32. It will be evident that the spring 38 constantly exerts its pressure to urge the valve member 33 downwardly, thereby tending to unseat the valve head 35 from the seat 38 at the lower end ofthe valve element 25. The spring 38 is ofa predetermined pressure so as to control the differential which must be built up across the valve member 33 in order to open the same, as will be hereinafter explained.

Both the outer valve element and the inner valve member 33 are operable by the pressure differential thereacross and the particular differential which is necessary to actuate each is determined by the pressure of the respective springs and 38. It is desirable that the spring 30 which acts upon the outer valve element 25 be of a lighter pressure than the spring 38 which acts upon the inner valve member 33 and the operation will be described with the springs so constructed. However, it is pointed out that under certainconditions it may be more desirable to make the spring 30 the stronger spring,

with the spring 38 lighter in pressure.

In the operation of the device, said device is connected to the well tubing as shown in Figure 1 and the liftingv fluid is introduced into the annular 4space between the tubing and the casing, this lifting fluid being at a predetermined or known pressure. For the purposes of this description, it will be assumed that the pressure in the annular space is to be maintained at 300 pounds. It will further be assumed that the pressure of the spring 30 is 100 pounds, while the pressure of the spring 38 is 150 pounds. With no liquid column or pressure within the well tubing, the 300 pounds pressure of the lifting gas in the casing will act through the inlets 23 against the lower ends of the valve element 25 and valve member 33 to hold both o f these valves in a seated or closed position, as shown` in Figure 4.

As the well liquid column builds up within the tubing Il, the pressure of this liquid column will act upon the upper ends of both valve element 25 and valve member 33, this pressure being added to the springs 30 and 3 8 which are tending to move these parts toward an open or unseated position. Since the heavier spring 38 has' a pressure of 150 pounds. as soon as the well liquid pressurereaches 151 pounds which added to the spring makes a total of 301 pounds,

the inner valve element 33 is moved downwardly to an unseated position, whereby the lifting fluid from exteriorly of the housing may flow upwardly through the bore 28 of the valve 25 and into the well tubing. Almost immediately the admission of this lifting fluid which has a pressure of 300 pounds will act to permit the spring 30 to immediately open the outer valve member 25, whereby both inner and outer valves are open, as shown in Figure 2. Opening of both valves permits a. large volume of the lifting iluid to enter the well tubing and to move` the liquid column upwardly therein. This large volume is necessary and desirable in order to start the fluid moving toward the surface and obviously upward movement of flow of the well liquid will lichten the load. with the result that thepressure acting against the upper ends of the valves gradually decreases.

When'the load or pressure within the well tubing is 'decreased to less than`200 pounds. then the outer valve element-25 will be' again moved vtiered inoperative.

casing .is permitted to reach an. excessive pressure, a valve member; dependent for 'its operation upon pressure dinerentials might be ren- For example, Aifj the llifting fluid pressure in the casing built'up to 600 pounds and a 100, pound'spring was acting on the valve.

upwardly toits seated position because the lifting iluid pressure'acting against its lower end eIement, the wellliquid pressure Vwould have to build up in excess of 500 pounds in orderto will be vgreater'than the combined' pressure of the wellliquid or load in vthe tubing and the spring 30;, As -soonras theouter valvexelement 25 closes, a continuedadmission of lifting iluid occurs through the channels 34 of the inner valve member 33 butthis continued admission isof a lesser volume.- As soon as the'liquid column hasl been moved andis in motion under the impetus of the originally large volume, only ar` lesser volume is necessary to continue the lifting of said column. `The inner valve 33 remains in an open position until the pressure or..load lwithinl the,

well tubing has been reduced below 150 pounds, whereby this pressure or load combined with the spring 38 is not sufficient to hold the inner valve Vopen against the 300 pounds lifting fluid pressure.' When this occurs theinner valve closes, the parts moving to the position shown in Figure -wlth thefinnervalve member 33 controlling the 4. They remain so until such time as the liquid column again builds up to re-open both valves, then successively close them in the manner above described.

It will be obviousthatthe device provides an eilcient means for lifting orraising the well liquids within the tubing. Uponinitial operation,

both valves' are open so as to admit' a -large volume of lifting uid whichis needed to start the well liquids movingv upwardly toward the surface; after thev Well. liquid lcolumn is in motion liquids is complete.

Under certain conditionsit may -be'desirable to "Q admit only a small volume of lifting uid at the i start and then increase'such, volumeiandby reversing the springs, that is,'p la'cing thestronger spring on'the outer or-largevalve and the weaker spring on the smaller or inner valve, this could be accomplished. 'Also it Vmay be desirable to 'further varythe volume throughoutthe opera.

tion of the device and this could be readilydone by adding oneor more telescoping valves to "thev assembly, with each valvehaving a diierent strength' spring. A'With such arrangement allA valves would' open at the start of the operation and then would successively or progressively close` to reduce thevolume' of admitted lifting iluid as the load lightened within the wen tubing. As

has been stated, -the device'is described as conbe maintained at 300 pounds, the;` spring 30ar actuatethevalve.v Well conditions'might be such that 5130 pounds could' never be built up in the well tubing and', therefore, in'-' wells where .ex-

cessl formation-pressuremay enter-the casing, it. is desirableto provide a relief or stabilizing valve v which willprevent the casing pressure from exc eedingapredeterminedfpoint.-V

In Figure l6 the device isV shown .to operate admissionofjthe lifting fluid and the outer element 25 functionirlgsolely as a relief or stabiliz ing valve. When usingthe device in this manner, the outer valve element 25 is inverted, that is, the valve head. 26 4is disposedwithin the, bore 20 of the housing I'Efand is adapted to seat against an annular valve seat- 24a which is provided at the upper end .of the coupling I6 surrounding the upper portion of the'bore IBa of the said housing. Manifestlyn this case, the outer valve element 25 will seat to close the bore IBa upon a downward movement thereof.

Assuming that the lifting iluid pressure is to acting to hold the valve lelement 25 seated-in anda lesser volume of lifting vfluid is' required, the outer valve closes while 4thexinner valve re- I mains open until such time as the lifting ofthe Figure 6 will be set at 325 pounds.'v Under such condition, with substantially nov pressurel in the well tubing, 'which .will :be the condition `following the'lifting of al liquidcolumn immediately following-'operation of the inner valve element 33, the lifting iiuid pressure must be greater than 325poundszin 4order 'to `operi the valve element v25. If the lifting fluid-pressure is lexcessivethen -1 atthat point. the valve .25 would open to relieve this pressure and permitjits escape into the well `tubing, whereby the pressure exteriorly of the valve devicewill be maintained ratlits' desired point.

In thiscase, the inner valve member-33- func' itlons strictly as a* single differentially operatedv -valve and its spring 381s set for any desired operating condition. Assuming that the spring isse't at 1 50.pounds,lbuilding up of the welltubing pressure beyond 150 pounds will openithe-valvej member as andadmitnuia to llft'the welliiquidsi trolling the admission. of a liftingnuid into a well tubing 'but it will be apparent thatthe telescoping valve arrangement with the variation in spring strengths would make'it possible for the device to control the'admission of any fluid in `a. device capable o f-"operating the telescopin valves by a dilerential in pressure.

If the loadin lthe well'` tubing is lightenedsuillciently to reducethe pressure below pounds, the valve 33 will be closed to shut oifurther lilow.

It is at this time that the outer valve 25 will func- A tion `to relieve an excessive pressure in the well tubing if such excessive pressure is present.

- However, if the pressure in the casing exteriorly of the device never exceeds the desired pressure, the outer valve 25 will never come linto operation. Therefore, it is strictly a relief or stabilizing valve which will function to prevent the pressure in the casing from building up to an excessive point which might interfere with the voperation of the inner -valve member33.` Q

Itis pointed out that inthe form shown in Figl ure 6 it -wculdbe possible toemploytwo telescoping valves arrangedinthemanner shown in Flgures12 to 4 within an iouterrelieflor stabilizing valve so that the cilangeinvolume advantage could be .had along with the reliefjvalve-arrangement. The telescoping mounting v of-the valves makes is. possible -to` provide -a very 'simple and compact structure which facilitatesmanufacturexplanatory thereof and various changes in the size, shape and materials, as weil as 1n tne details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Lette Patent is:

1. A iiow control device for controlling the admission of a pressure fluid into a ow line including, a housing having a ilow passage which has one end communicating with the flow line and its opposite end communicating with the source of pressure iluid, a valve seat in said passage, a tubular valve element mounted in the passage and movable into and out of engagement with said seat, said valve element having one end exposed to the pressure of the pressure uid with its opposite end exposed t the pressure in the ilow line, whereby the valve element is actuated by the differential in the pressures acting on opposite sides thereof, resilient means acting on one side of the valve element for controlling the pressure diierential which is necessary to actuate the valve element, and a second valve member mounted within the tubular valve element for controlling the ilow through said element and having one end exposed to the pressure of the pressure uid and its opposite ends exposed to the pressure in the flow line, whereby the member is actuated by the diierential in such pressures, and a second resilient means acting on the valve member and of a different strength than the first resilient means for controlling the diierential which is required to actuate the valve member.

2. A ilow control device as set forth in claim 1, wherein the resilient means are coiled springs of different predetermined pressures.

3. A weil flow device for controlling the admisvsion of a pressure fluid into a well conductor and including, a housing having a ow passage for establishing communication between the interior and exterior of the housing, a plurality of valve elements in said passage for controlling now through said passage, each element having one end exposed at all times to the pressure exteriorly of the well conductor and its opposite end exposed to the pressure interiorly of said conductor, whereby said valve elements are actuated by the differential in the pressures acting thereon and individual means associated with each valve element for controlling the diierential across the valve required to actuate said element, each valve element being of a different size than the other elements whereby the elements permit a varying `volume of flow, and each element being set to be actuated by a different pressure diierential thereacross, whereby the elements are progressively actuated.

4. A well iiow device for controlling the admission of a pressure fluid into a well conductor and including, a housing having a ilow passage for establishing communication between the interior and exterior thereof, a tubular valve element in said passage movable to open and closed positions and having one end constantly exposed to the pressure exterior-ly of the-conductor and its opposite end exposed to the pressure interiorly of said conductor, whereby it is actuated by the differential in such pressures. a second valve member slidable within the valve element movable to open and closed positions and having one end constantly exposed to the pressure exteriorly of the conductor with its opposite end exposed to the pressure interiorly of the conductor, whereby said second member is also actuated by the diierential in pressures acting thereon, means associated with the valve element for controlling the pressure differential thereacross required to actuate the same, and means associated with the valve member for controlling the pressure differential thereacross required to actuate said member.

5. A well ow device as set forth in claim 4, wherein the valve element and valve member'are of diierent sizes, whereby when in an open position each permits a volume of iiow different from kthe volume permitted by the other.

6. Awell ow device as set forth in claim 4, wherein the means associated with the valve element is of a greater or lesser strength than the means associated with the valve member, whereby the element and member are actuated at various pressure differentials.

7. A well ilow device as set forth in claim 4, wherein the controlling means associated with the valve element and valve member are springs acting on said element and member, said springs being of different strengths, whereby the element and member are actuated at various pressure differentials.

8. A well ilow device for controlling the admission of a pressure uid into a well conductor and including, a housing having a iiow passage for establishing communication between the interior and exterior thereof, a tubular valve element in saidrpassage movable to open and closed positions and having one end exposed to the pressure exteriorly of the conductor and its opposite end exposed to the pressure interiorly of said conductor, a second valve member slidable within and entirely through the valve element movable to open and closed positions and having one end exposed to the pressure exteriorly of the conductor with its opposite end exposed to the pressure interiorly of the conductor, a spring acting on that side of the valve element which is exposed to the pressure interiorly of the well conductor, and -a spring of different strength acting on that side of the valve member which is exposed to the pressure interiorly of the tubing, said springs functioning to control the pressure differentials gecessary to actuate said element and said mem- 9. A well :dow-device as set forth in claim 8, wherein the valve element is of a larger area and when open permits a. larger volume of ow through the passage than the valve member.

10. A well ow device for controlling the admission of a pressure iiuid into a well tubing and including, a housing having a flow passage for establishing communication between the interior and exterior of the tubing, a main valve element in said passage for controlling flow through said passage and having one end exposed to the pressure exteriorly of the tubing with its opposite end exposed to the pressure interiorly of the tubing, whereby the valve is operated by a differential between such pressures, and a stabilizing valve also mounted in the housing and actuated by the pressure exteriorly of the tubing to maintain said exterior pressure substantially constant.

11.,A well iiow device for controlling the admission of a pressure fluid into a well tubing and including, a housing having a flow passage for establishing communication between the interior 11 and exterior of the tubing, a main valve element in said passage for controlling iiow through said passage and having one end exposed to the pressure exteriorly of the tubing with its opposite end exposed to the pressure interiorly of the tubing, whereby the valve is operated by a differential between such pressures, a relief valve also mounted within the housing and normally held ina closed position by a flexible means of predetermined pressure, the relief valve being exposed to the pressure exteriorly of the tubing,

wherebyv when such pressure exceeds that of the 'flexible means the relief valve is opened to reduce said pressure exteriorly of the tubing to the predetermined point as controlled by the pressure of the flexible means.

`12. A well flow devicefor controlling the admission of a pressure iluid into a well conductor and including, a Well conductor, a housing adapted tobe connected to said conductor and tending entirely therethrough for controlling flow through said element and through the housing into theconductor.

v13. A well flow device as set forth in claim 8, i wherein the main valve member has one end exposed to the pressure 'exteriorly of the tubing L and its opposite end exposed to the pressure interiorly ofv said tubing, whereby said valve member is actuated by the differential in such pressures.

14; A well ow devicefor controlling the admission of a pressure fluid into ya well tubing and includinma well tubing a housing mounted on said tubing andhaving a flow passage for estab- "lishingcommunication between the interior and- Aexterior ofthe tubing, a valve seat within the housing, a tubularvalve element adapted to engage said seat to shut of! flow past the seat, said valve having opposite ends exposed to the pressure exteriorly and interiorly of the tubing, a coaxial valve member mounted within the valve element and extending entirely therethrough for controlling flow through said element and through the passage of the housing, said valve member having one end exposed to the pressure exterioily of the tubing and its opposite end exposed to the pressure. interiorly of the tubing, a spring acting on the tubular valve element and adding its pressure to the pressure interiorly of the tubing, and a spring acting on the valve and adding its pressure to the pressure interiorly of the tubing, said springs being of predetermined strengths and functioning to control the pressure differential which is required to actuate said valve.

15. A well ow device including, a well conductor, a housing connected on said conductor and having a ow passage therein for establishing communication between the interior and exterior of said conductor, a relief valve mounted Within the housing actuated to admit pressure from exteriorly of the housing and conductor to the interior thereof when the exterior pressure exceeds a predetermined point. and a main valve member within the housing operable independently of the relief valve, said main valve member having one end exposed to the pressure exteriorly 'of the conductor and its opposite end exposed to the pressure interiorly thereof, whereby said valve is actuated by the differential in'such pressures.

LYNDON L. HAR'I'MAN,

REFERENCES CITED The following referencesare of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 423,003 Vielhaber Mar. 11, 1890 1,153,770 Dayman Sept. 14, 1915 1,884,548 Boynton Oct. 25, 1932 2,365,892 McLeod Dec. 26, 1944 

